Thermally-operated circuit controller



G. H. WHITTINGHAM TBERMALLY OPERATED CIRCUIT CONTROLLER June 23, 1925..1,543,408

Filed Aug. 29, 1922 Patented June 23, 1925.

. UNITED STATES PATENT OFFICE.

GEORGE H. WHITTINGHAM, OF BALTIMORE. MARYLAND, ASSIGNOR TO MONITORCONTROLLER COMPANY, OF BALTIMORE, MARYLAND, A CORPORATION OF MARY- LAND,

THERMALLY-OPERATED CIRCUIT CONTROLLER.

Application filed August 29, 1922. Serial No. 584,939.

T 0 all whom it may concern:

Be it known that I, Gnoncn H. \VHITTIXG- HAM, a citizen of the UnitedStates, residing at Baltimore, in the State of Maryland, have inventedcertain new and useful Improvements in Thermally-Operated CircuitControllers, of which the following is a specification.

This invention relates to improvements in thermally operated relays forcontrolling electric circuits. The relay is adapted particularly for usein connection with electric motors, as a load limit device, to cause themain switch or contactor to open and dis connect the motor from thesupply circuit in case of overloading of one or more of the motorcircuits. various other uses. In the present invention, the relay isadapted to open the controlled circuit when the thermostat is heated andto leave this circuit 0 en when the thermostat cools, the relay t usserving the function of a cut-out in the controlled circuit.

The invention comprises a base of insulating material upon which theseveral parts, with the exception of the heating elements, are mounted,these parts including a bracket projecting above and extending over thebase, a contact lever fulcrumed against this bracket, a springinterposed between the base and the lever at one side of its fulcrumpoint, said spring tending to rock the lever toward its closed position,and one or more thermal expansion elements interposed between the baseand the lever, at the opposite side of the fulcrum point, and adapted torock the lever to open position, against the action of the spring, whensaid elements or any of them are heated beyond a predetermined degree. Astationary contact member is secured to the base and a metal connectoris arranged between this contact piece and the contact lever so that itmay be gri ped between these parts by the pressure 0 the spring, whenthe thermostat elements are contracted, and will be released and droppedinstantly out of engagement with the lever when the latter is movedsufiiciently by one of the thermostats to relieve the pressure on theconnector. Thus, although the lever is moved very slowly by thethermostats, a quick break in the controlled circuit is provided and thecircuit remains 0 en after the the m stat a o ed and the ever has .re-

The relay has. however,

turned to its normal position unless the connector is manually returnedto its upper position. The connector is returned manually by a simplere-setting device. Each thermostat comprises a closed metallic chamberfilled with an expansible liquid. one wall of the chamber consisting ofa corrugated tube which is axially expansible and adapted to actuate thelever. Vertically adjustable sockets are arranged in the base and theexpansion elements are supported in these sockets. By adjusting thesockets the ex pansion elements may be adjusted with respect to thecontact lever to vary the time of the actuation of said lever by saidelements. The heating elements are formed to fit within sockets orcasings in the expansion elements. and these heating elements,

which are connected in the circuit or circuits 1 to be protected, may bereadily removed and replaced by other similar elements of differentcurrent-carrying and heating capacities, according to the current volumein the circuit or circuits to be protected and the heating effectdesired in the thermostats.

In the accompanying drawing,

Fig. l is a front elevation of the cut-out, partly in section;

Fig. 2 is an end view of the base;

Fig. 3 is a plan view of the connector;

Fig. 4 is a central vertical section through the cut-out, taken fromfront to rear;

Fig. 5 is a section on the line 55 of Fig. 4;

Fig. 6 is a central vertical section through one of the thermostats,showing a coiled heating element; and,

Fig. 7 is a perspective view of a stamped heating element.

Referring to the drawing, a represents a base of insulating materialupon which the parts of the cut-out, except the heating coils, aremounted. Upon this base is secured an upstanding bracket 6, having itsupper end 6 turned forwardly over the base and thence downwardly, asshown. This downwardly turned part of the bracket is shaped to provide awide tongue I) atits center which enters atransverse slot 1, in a switchlever s, and two bearings 6 in line with the tongue, which bearings formfulcrum points for the lever. The ever comprises a relatively wide part2 and a longer and narrower part 3, which is bent at right angles to thepart 2. The part 2 of the lever is pressed upwardly against the fulcrumpoints 6 by a spring 4, which is interposed between the base and therear end of the lever. This spring, as shown, is coiled about a threadedrod 5, which extends through the top of the bracket and into the base.The part 2 of the lever thus occupies a substantially horizontalposition, and the arm 3 of the lever extends downwardly in front of thebase. The lower part of the arm is preferably made of brass and has aninwardly off-set portion 3 substantially parallel with the major portionof the arm, and an outwardly inclined end portion 3". The part 3 isadapted to bear against a square relatively thick and heavy copperconnector 0 to hold this connector, by the pressure of the spring 4,against the downwardly extending part 6 of a fiat metal strip 6, whichis secured to the underside of the base. The connector has a centralopening 7 preferably countersunk from both sides so that it can dropfreely downward on a rod 8, which passes through the opening, and theedges of the connector, which are engaged by the lever and the metalstrip, are preferably rounded as shown at 7 so that the connector maydrop without hindrance by these parts when the lever moves sufficientlyto release the connector. The rod 8 constitutes part of the re-settingdevice (1. -This rod extends upwardly through a hole 9 in the base, anda nut 8 on the rod above the base serves as a support for the rod. Thelower end of the rod carries a knob 8 on to which the connector dropswhen released by the lever, as indicated in dotted lines in Fig. 4. Toplace the connector in position to be gripped by the lever it is onlynecessary to push the resetting device upwardly until the connector liesagainst the underside of the base. When the re-setting device isreleased, it drops down and remains suspended on the nut 8. In movingupward, the connector bears against the inclined lower end 3 of thelever and forces it outwardly. In its uppermost position the connectoris gripped between the lower end of the vertical part 3 of the lever andthe opposing flat contact piece 6".

One terminal 10 of the circuit to be controlled by the cut-out isconnected to a bolt 12 which passes through the bracket 6 and securesthe same to a switchboard e, and the other terminal 10 of the circuit isconnected to a bolt 13 which passes through the contact strip 6 and theswitchboard. From the conductor 10 the current flows through the bracketand contact arm to the connector and thence through the contact strip 6to the conductor 10%....The release of the connector interrupts thecircuit and leaves it open until the connector is moved device.

u'pward manually by means of the re-setting device.

Two thermostats f, f are shown for actuating the switch lever inopposition to the spring, each thermostat bcin capable of actuating thelever independ ently of the other thermostat. There may be one or anynumber of thermostats, according to the number of circuits to beprotected by the The thermostats are alike and each comprises anexpansion element, supported by the base, and a heating element F,supported upon the switchboard and extending into a casing or socket inthe expansion element. As shown, the expansion element comprises anouter annularly corrugated tube 14, connected at one end by a fluidtightjoint 15 with a tube 16 which extends into the corrugated tube and hasits inner end 16 closed. The corrugated tube has a cap 17 at its freeend, this cap having a nipple 17 through which the tube may be filledwith an expansible liquid 18. This nipple, after the tube has beenfilled, is closed by a plug 17. The heating element, as shown in Fig. 6,comprises a coiled wire 19, adapted to fit within the inner tube orcasing 16 and having its terminals connected to the metal eyelets 20 ina flat piece of insulating material 21 which supports the coil. Forheavy currents, the heating conductor may take the form shown in Fig. 7.In this figure, the conductor is a stamped strip of metal 19 doubledupon itself at the center and having outwardly turned ears 19 which areperforated, as

shown at 20. The strip 19, suitably insulated, is to be inserted in thesocket in the expansion element. The heating elements are detachablyconnected to binding posts 21 which project from the switchboard belowthe base of the relay, and they are secured to these binding posts byscrews 21" which pass through the eyelets 20 or the perforations 20 inthe heating elements.

The ex ansion elements are arranged vertically in front of the fulcrumpoint of the switch lever s, and are adapted to rock the lever inopposition to the spring 4, when these elements, or either of them, reheated. As shown, the base is formed wit threaded openings 22 in whichare fitted threaded sockets 23, of insulating material, and theexpansion elements are supported in these sockets with the open ends ofthe inney casings or tubes 16 downward. Upon the u r end of eachexpansion element is a bus mg 24, of insulating material, which extendsthrough an opening 25 in the horizontal part of the lever in advance ofits fulcrum point. These bushings are provided with annular shoulders 24which rest upon the caps 17 of the corrugated tube. The lever has atransverse rib 2 on its underside which is adapted to be engaged by theshoulders 24' on the bushings when the lever is supported by theexpansion elements. The expansion elements may be adjusted toward andfrom these ribs b sockets 23, and this adjustment is important in orderto advance or delay the time in which the thermostat will open theswitch with a given current flowing in its heating conductor. When thefluid in the expansion element is heated, the corrugated tube isexpanded forciblyagainst the lever and moves the latter to openposition. When the liquid cools, the pressure of the spring prevails andthe lever is rocked to its closed position so that it may firmly engagethe connector, and make a good electrical contact therewith when theconnector is raised to its upper position.

If the relay or cut-out is used for controlling the pilot circuit of aswitch for connecting a polyphase alternating motor to a supply circuit,the heating elements will be connected in separate circuits of themotor. Thus, in Fig. 1, the conductors 26, 26', are connected throughthe heating coil of one thermostat, and the conductors 27, 27', areconnected through the heating coil of the other thermostat, and theseconductors may represent different circuits of a polyphase motor. Itwill be evident that excessive current flow in either of the circuitswill cause the corresponding thermostat to ex- I pand and move theswitch lever to release the connector. This will cause opening of thecircuit 10, 10, which latter may represent the pilot circuit of themain'switch for connecting the motor to the supply clrcult. It isbelieved to be unnecessary to illustrate the motor and main switch andtheir connections since these are well known and the device of thepresent invention is useful for other purposes than motor control.

The operation of the device will be clear from the foregoing withoutfurther description.

What I claim is:'

1. In a thermally operated circuit controller, a switch lever, a springtendlng to rock said lever in one direction and a plurality ofthermostats for rocking said lever 1n the opposite direction, eachthermostat comprising a closed chamber contalnlng an expansible liquidand having a tubular annularly corrugated wall adapted bear against saidlever, and means for ad usting said chambers independently toward andfrom the lever.

2. In a thermall operated circuit controller, a base, a fiilcrumsupported upon and above the base, a switch lever having a bearing onsaid fulcrum, a spring bearing upwardly on said lever at one slde of thefulcrum. and a thermostat adapted to bear upwardly onsaid lever at theopposites de of the fulcrum, said thermostat comprising turning thethreaded a closed chamber containing an expansible liquid and having alongitudinally expansible tubular wall vertically arranged between thebase and the lever.

3. In a thermally operated circuit controller, a base, a fulcrumsupported upon and above the base, a switch lever having a bearing onsaid fulcrum, a spring hearing upwardlyon said lever at one side of thefulcrum, and a thermostat adapted to bear upwardly on said lever at theopposite side of the fulcrum. said thern'iostat comprising a closedchamber containing an expansible liquid and having a longitudinallyexpansible tubular wall and a socket adjustably mounted in the base andadapted to receive said chamber.

4. In a thermally operated circuit controller, a base, a stationarycontact thereon, a switch lever, a spring normally pressing said levertoward said contact, a connector'adapted to be held against the contactby the lever and to drop by gravity when the lever is moved away fromthe connector, and a thermostat adapted to move the lever in oppositionto the spring.

5. In a thermally operated circuit controller, a base, a stationarycontact thereon, a switch lever, a. spring normally pressing said levertoward said contact. a connector adapted to be held against the contactby the lever and to drop by gravity when the lever is moved away fromthe connector, and a thermostat adapted to move the lever in oppositionto the spring comprising a closed chamber containing an expansibleliquid and having a longitudinally expansible tubular wall and means foradjusting said chamber toward and from the lever.

6. In a thermally operated circuit controller, a base, a stationarycontact thereon, a switch lever, a spring normally pressing said levertoward said contact, a connector adapted'to be held against the contactby the lever and to drop by gravity when. the lever is moved away fromthe connector, a thermostat adapted to move the lever to release theconnector, and means for resetting the connector.

7. In a thermally operated circuit controlling device, a base, astationary contact thereon, a lever having a horizontal part pivotallymounted over the base and a depending part opposed to said contact, aconnector adapted to fit between said latter part and said contact, aspring for pressing said lever into engagement with the connector and athermostat comprising a vertically arranged expansible tube interposedbetween the base and the lever, for moving the lever to disengage theconnector.

8. In a thermally operated circuit controlling device, a base, astationary contact thereon, a lever having a horizontal part pivotallymounted over the base and a depending part opposed to said contact, aconnector adapted to fit between said latter part and said contact, saidconnector comprising a metal plate having an opening therethrough, aresetting rod extending loosely through said opening and suspended fromthe base, a spring for pressing the lever into engagement with theconnector, and a thermostat on the base adapted to move the lever inopposition to the spring.

9. In a thermally operated circuit controller, a base. a fulcrumsupported upon and above the base, a switch lever having a bearing onsaid fulcrum and extending over and downwardly in front of .the base,said lever having its lower end inclined downwardly and outwardly fromthe base, a stationary contact on the base, a connector adapted to fitbetween the lever and contact and to drop by gravity when the lever ismoved away from the contact, a spring normally pressing the lever towardthe contact, and a thermostat interposed between the base and lever formoving the latter in opposition to the spring.

10. A thermally operated circuit controller comprising a base, a socketvertically adjustable on the base, a contact lever extending over thebase and having an opening in line with said socket, a thermostatcomprising a longitudinally expansible tube fitting in said socket andhaving a part extending through said opening, and a spring normallypressing the lever toward said tube.

11. A thermally operated circuit controller comprising a base, astationary contact, a lever fulcrumed above the base, a spring normallypressing the lever toward the contact, a thermostat, comprising an outerexpansible tube and an inner tube, arranged between the base and lever.a heating element projecting upwardly into the inner tube, and bindingposts below the tube for supporting said element.

.In testimony whereof I afiix my signature.

GEORGE H. \VHITTINGHAM.

